diff --git a/cmd/mtredisalize/changetracker.go b/cmd/mtredisalize/changetracker.go
index 9f90d86..6024e97 100644
--- a/cmd/mtredisalize/changetracker.go
+++ b/cmd/mtredisalize/changetracker.go
@@ -39,15 +39,13 @@ func (ct *ChangeTracker) BlockChanged(key []byte) {
 func (ct *ChangeTracker) FlushChanges(url string) (err error) {
 	log.Println("change flush triggered")
 	var oldChanges map[quantizedXZ]bool
-	var sendNotification bool
 	ct.mutex.Lock()
-	oldChanges = ct.changes
-	if len(oldChanges) > 0 {
-		sendNotification = true
+	if len(ct.changes) > 0 {
+		oldChanges = ct.changes
 		ct.changes = make(map[quantizedXZ]bool)
 	}
 	ct.mutex.Unlock()
-	if !sendNotification {
+	if oldChanges == nil {
 		return
 	}
 	go func() {
@@ -57,15 +55,14 @@ func (ct *ChangeTracker) FlushChanges(url string) (err error) {
 			changes[i] = change
 			i++
 		}
-		var err error
-		var encoded []byte
-		if encoded, err = json.Marshal(changes); err != nil {
+		var buf bytes.Buffer
+		encoder := json.NewEncoder(&buf)
+		if err = encoder.Encode(changes); err != nil {
 			log.Printf("WARN: encode changes to JSON failed: %s", err)
 			return
 		}
-		var buf bytes.Buffer
-		buf.Write(encoded)
-		if _, err = http.Post(url, "application/json", &buf); err != nil {
+		if _, err = http.Post(
+			url, "application/json", bytes.NewBuffer(buf.Bytes())); err != nil {
 			log.Printf("WARN: posting changes to %s failed: %s", url, err)
 		}
 	}()